fflush（stdin）函数不起作用

Question

我似乎无法弄清楚这段代码出了什么问题：

#include <stdio.h>
#include <ctype.h>
#include <string.h>
#include <stdlib.h>


#define MAX 100
#define TRUE 1
#define FALSE 0

char sect_cat;
char customer_name[MAX];
char customer_number[MAX];      /* error handling is easier */

int prev_unit = 0;
int current_unit = 0;
int consumed = 0;
int set = FALSE;

float init_bill;
float tax;
float total_bill;


    void get_userinfo()
    {

            printf("Enter sector category: ");
            scanf("%c", &sect_cat);
        printf("Enter customer name: ");
        fflush(stdin);
        scanf("%sn", &customer_name);

        set = FALSE;
        while (set == FALSE)
        {
            printf("Enter customer number: ");
            fflush(stdin);
            scanf("%s", customer_number);

            int i;
            int error;
            for (i=0, error=0; i<strlen(customer_number); i++)
            {
                if (isdigit(customer_number[i]))
                {
                }
                else
                {
                    error = 1;
                }
            }
            if (error == 0)
            {
                set = TRUE;
            }
            else
                printf("ERROR: Only numbers are allowed\n");
        }

        printf("Enter previous unit: ");
        fflush(stdin);
        scanf("%d", &prev_unit);

        set = FALSE;
        while (set == FALSE)
        {
            printf("Enter current unit: ");
            fflush(stdin);
            scanf("%d", &current_unit);

            if (prev_unit > current_unit)
            {
                printf("ERROR: Current unit must be larger than previous unit\n");
            }
            else
                set = TRUE;
        }
        consumed = current_unit - prev_unit;
    }



int main()
{


/* Introduce program to users */

        printf("\nThis program computes your electric bill based on these sector categories\n\n");

    printf("\tResidential(R)\n");
    printf("\tIndustrial(I)\n");
    printf("\tCommercial(C)\n\n");

    printf("Press any key to continue...");
    fflush(stdin);
    getchar();  

####################编辑

应用templatetypedef的解决方案，该程序现在等待用户输入customer_name。但是，输入带空格的字符串会导致错误，并且程序假定空格后的单词是为下一个提示输入的。

Enter sector category: r
Enter customer name: George of the Jungle
Enter customer number: ERROR: Only numbers are allowed
Enter customer number: ERROR: Only numbers are allowed
Enter customer number:

Answer 1

fflush函数不会从输入流中刷新数据；相反，它用于将输出流中缓冲的数据推送到目标。已记录在here中。从this earlier SO question中可以看出，尝试使用fflush(stdin)会导致未定义的行为，因此最好避免这种情况。

如果您想吃掉用户输入字符后输入的返回字符中的换行符，请考虑以下内容：

Answer 2

我认为您打算写fflush(stdout)而不是fflush(stdin)。

Answer 3

[fflush应该与输出流一起使用，请参阅文档here